1. Field of the Invention
The present invention relates to systems for assessing bone characteristics. More particularly, the present invention relates to a system that performs biochemical and densitometric assessments of bone material to provide practitioners with bone characteristic data for evaluation of a patient's bone material for diagnosis and management of bone related disease.
2. Description of the Related Art
The diagnosis and management of bone related disease, such as osteoporosis, typically requires information about bone turnover and bone mass. Determinations of bone turnover have historically been performed utilizing standard serum and/or urine laboratory tests including fasting calcium/creatinine, hydroxyproline, alkaline phosphatase and/or osteocalcin/bone growth protein utilizing standard high pressure liquid chromatography (HPLC) techniques. To illustrate, whenever bone formation occurs (calcium deposition) or bone resorption occurs (calcium breakdown), various chemical reactions occur within the body which elevate the presence of certain indicators in the blood and urine suggesting changes in the calcium/bone mineral status.
Recently, several new bone specific assays have been developed which enable bone turnover to be evaluated with an ELISA/EMIT immunoassay format. Descriptions of these immunoassay formats can be found in U.S. Pat. Nos. 5,973,666, 5,320,970, 5,300,434 and 5,140,103. The labeling for the new assays utilize a biochemical marker to quantify bone resorption and/or formation and permit a trained practitioner to assess bone turnover.
Bone mass determinations, on the other hand, have been traditionally performed by using various x-ray based techniques including single and dual-photon absorptiometry (SPA and DPA), quantitative computed tomography (QCT), and dual-energy absorptiometry (DXA).
To reduce the time necessary to determine if bone resorption or formation is occurring and to permit a practitioner to project future bone characteristics, a system which combines a biochemical bone measuring system that measures, for example, bone turnover, with a densitometric bone measuring system that measures, for example, bone density is desirable.
Further, the x-ray based equipment emits ionized radiation in the form of x-rays and requires a licensed technician to operate the equipment. In addition, this equipment is structurally large and constructed to house, for example, an x-ray source and an x-ray detector, and provides a large table area to position the patient for examination. As a result, such x-ray based equipment occupies a large floor area. In addition, since x-rays are emitted by such equipment, certain safety precautions must be followed to limit human exposure to the emitted rays.
High frequency ultrasound has recently become an alternative technique for determining preliminary assessments of bone status. Measuring the bone density with ultrasound is currently more desirable over some of the above mentioned techniques since there is no ionizing radiation in the form of x-rays produced by ultrasound. As a result, a licensed x-ray technician does not have to be employed to operate the ultrasonic measuring equipment and the environment where the instrument is located and operated is not strictly regulated. In addition, ultrasonic measuring equipment can be manufactured significantly smaller in size and weight than the above-mentioned x-ray type bone density measurement equipment and is suitable for installation in private offices or medical facilities where space is typically at a premium.
The parameters that can be determined using ultrasound include the speed-of-sound, the attenuation of the ultrasound signal and/or combinations of the above as it penetrates bone and tissue. These parameters provide general characteristics relating to bone density and the risk of future fracture.
Although the above described assay techniques provide a practitioner with information regarding the rate of bone resorption or formation, the results from such techniques are of limited value unless a baseline level of bone mass can also be established. Measuring bone density provides practitioners with baseline bone density information and after successive measurements over a period of time, e.g., one year, may also permit the practitioner to determine if bone resorption or bone formation is occurring. However, this process takes a period of time (nominally, approximately one year) to determine if there is bone resorption or formation occurring. Biochemical markers which evaluate physiological status directly are capable of evaluating the change in the amount of bone formation or resorption, for example, in response to therapy, in a matter of months. Thus, to quickly and accurately obtain an assessment of bone formation or resorption a practitioner typically utilizes both measurements to obtain the necessary bone characteristic data.
Thus, a need exists for a bone measuring system capable of performing various types of assessments of bone material and providing a practitioner with bone characteristic data in the form of, for example, graphical display results, to permit the practitioner to diagnose and manage bone related disease.
A need also exists for a compact and inexpensive system that may be installed in a practitioner's office or like location and that reduces the time necessary to determine bone resorption or formation and to permit a practitioner to diagnose and manage bone related diseases.